This invention is related to methods of depositing films of metals or metal oxides with embedded nanoparticles, from metal complexes or precursor solutions. The invention also relates to the use of such films in a variety of applications including but not limited to microelectronics fabrication.
Usually films of inorganic materials are deposited by chemical or physical vapor deposition although in some cases Sol gel or metal organic deposition have been used.
None of these methods, however, are able to pattern films of materials and, therefore, must be used with other methods to form the patterned structures normally used in the construction of microelectronic devices or circuits.
The photochemical deposition method differs from the above two methods in that the reaction which drives off the organic components is photochemically activated. Hybrid methods often use light as the energy source, but the light used initiates a thermal rather than a photochemical reaction.
U.S. Pat. No. 5,534,312 to Hill et al. discloses a method for the deposition of a variety of metal and metal oxide systems using photochemical deposition. This process relies upon the construction of an optical quality film of the precursor material in order to provide (macroscopic) optical homogeneity during the lithographic process.
The formation of nanoscale particles of different materials is known in the art. For example, U.S. Pat. No. 5,984,997 to Bickmore et al., incorporated herein, discloses a process for producing nanoscale powders by mixing an emulsion comprising all of the elements of the desired powder composition and a combustible fuel, and then combusting that emulsion to produce a powder. The ""997 patent process discloses the production of many types of powders, including particles and nanowhiskers of simple, doped, and polymetallic powders.
Forming a material with imbedded nanoparticles through use of a precursor material is disclosed in U.S. Pat. No. 5,851,507 to Pirzada et al., incorporated herein, where a continuous process is used to produce nanoscale powders from different types of precursor materials by evaporating the material and quenching the vaporized phase in a converging-diverging expansion nozzle. However, the ""507 patent does not disclose a photochemical technique of converting the precursor material to a metal or metal oxide film with imbedded nanoparticles. Also, M. Cahay, et al., Quantum Confinement: Nanoscale Materials, Devices, and Systems, Electrochemical Soc. Proceedings Volume 97-11, pp. 35-46 1997, incorporated herein, describe embedding nanoparticles in a thermal sol gel matrix but also does not disclose converting or patterning a thin film deposited from a precursor material.
The use of nanoparticles or nanoscale particles in passive components has previously been found to be beneficial. For example, U.S. Pat. No. 5,952,040 to Yadav et al., incorporated herein, discloses nanosize powders which are used to form the ceramic layers of passive electronic components. The ceramic layers containing nanoscale powders are deposited between electrodes to form an electrode/ceramic/electrode structure. The ceramic layer is dried at low temperatures to prevent interdiffusion problems of the nanoscale powders. However, the ""040 patent does not disclose a means to distribute the nanoscale powders directly within a metal or metal oxide film, nor does the ""040 patent teach a photochemical technique of converting the precursor material to a metal or metal oxide film.
The present invention is an extension of these technologies and discloses a means to embed nanoparticles in metal or metal oxide films for various lithographic applications.
The present invention discloses a method for depositing nanoparticles in a thin film. The nanoparticles are dispersed in a precursor solution which is deposited on a substrate and converted into a metal or metal oxide film. The precursor film may be deposited on the surface by a variety of methods. The conversion to metal or metal oxide film can be achieved by photochemical reaction or by the impact of an ion or an electron beam. The resulting metal or metal oxide film thereby contains embedded nanoparticles. By use of a mask or a directed beam, the metal or metal oxide film can be patterned. By altering the atmosphere in which the pattern is formed, the composition and/or properties of the resulting metal or metal oxide film can be altered.
Such films can be used in a variety of applications such as diffusion barriers, electrodes for capacitors, conductors, resistors, inductors, dielectrics, or magnetic materials. The resulting film may be amorphous or crystalline based on the application. The nanoparticle material may be selected by one skilled in the art based on the particular application.